Molybdenum and various alloys, consisting predominantly of molybdenum, are in widespread commercial use in many everyday as well as special applications. The unique physical, chemical and mechanical properties of this refractory metal and its alloys, particularly at elevated temperatures, are responsible for the general field application to high temperature equipment and hot structural components.
The most common commercially available wrought products comprise essentially pure or lightly alloyed molybdenum, originally consolidated by either powder metallurgy or vacuum-arc-casting methods and two principal molybdenum alloys:
1. TZM molybdenum alloy, approximately 0.5% titanium, 0.08% zirconium, balance molybdenum (by weight) PA1 2. molybdenum -- 30% tungsten alloy, approximately 70% molybdenum, 30% tungsten (by weight).
Because molybdenum-base materials are subject to gross oxidation at temperatures above about 1200.degree. F, with the profuse evolution of so-called molybdic oxide "smoke", that often renders both handling and fabrication rather hazardous, as well as causing significant material losses, the present process was invented and applied to molybdenum and various alloys.
It has heretofore been proposed to reduce or eliminate such "smoking" problems by performing the red hot molybdenum fabrication in a protective environment or by coating the billet to prevent oxidation attack thereof. Economic factors have precluded real success for either technique due to excessive process cost and/or product losses.
The process of the present invention provides a simple, ecologically clean, energy conservative, and commercially acceptable procedure for the fabrication of molybdenum-base wrought products, employing conventional working methods such as forging, round and flat rolling, or similar processes. The resultant products produced in accordance with the present invention exhibit at least equivalent mechanical properties, and in many instances exhibit unexpected superior properties to those produced in accordance with the prior art practices of red hot fabrication.